1. Field of the Invention
The present invention relates to a method for manufacturing a flexible printed circuit board (PCB), and in particular to a method and fixture for manufacturing a flexible printed circuit board by employing a rigid printed circuit board manufacturing system without requiring a special manufacturing system.
2. Description of the Background Art
In general, types of printed circuit boards (hereinafter, referred to as `PCB`s) are classified into a rigid type of PCB made of phenol, epoxy and the like, and a flexible type of PCB made of polyimide.
There have been known various methods for manufacturing the rigid type PCB. The rigid type PCB is typically manufactured by transferring sheets of a rigid raw material on a conveyer and by carrying out a stacking or laminating step, a circuit forming step, a metal plating step and a cleaning step thereon.
FIG. 1 is a schematic process view illustrating a conventional method for manufacturing a flexible type PCB by using a flexible PCB manufacturing system.
The flexible PCB is manufactured of a soft raw material having a thickness of approximately 0.1 mm which may be easily bent. Accordingly, as shown in FIG. 1, the flexible PCB is manufactured by a manufacturing process called a reel-to-reel or roll-to-roll process which is one of the known flexible PCB manufacturing methods.
That is, a flexible sheet 10 is consecutively moved from a supply reel (S) to a take-up reel (T), a copper foil (not shown) being stacked or laminated onto at one or both surfaces of the flexible sheet 10, and passed through a manufacturing system 20, thereby manufacturing the flexible PCB.
However, the flexible sheet 10 is easily bent or twisted during the manufacturing process, thus reducing productivity.
In addition to the rigid PCB manufacturing system that has been popularly used, a special system is necessary to perform the conventional method for manufacturing the flexible PCB.
Accordingly, the following method is employed so that the flexible PCB can be manufactured by using merely the rigid PCB manufacturing system without requiring an additional specialized system.
FIG. 2 is a plan view illustrating a constitution for manufacturing a conventional flexible PCB using the rigid PCB manufacturing system, and FIG. 3 is a cross-sectional view taken along line III-III' in FIG. 2.
Referring to FIGS. 2 and 3, the flexible sheet 10 is adhered to a supporting plate 40 with an adhesive 30, and then the manufacturing process is carried out using the rigid PCB manufacturing system.
However, when the flexible sheet 10 is adhered to the supporting plate 40, the adhesive 30 is applied to the entire surface of both sides of the flexible sheet 10. As a result, the flexible sheet 10 may be undesirably bent or curved when it is separated from the supporting plate 40.
In addition, the adhesive 30 remains on the surface of the flexible sheet 10, and thus it is necessary to remove the remaining adhesive by a special removing process. Accordingly, the number of the processes is increased.
While the flexible sheet 10 is adhered to the supporting plate 40, if the flexible sheet 10 is not sufficiently flat, it is difficult to exactly form a circuit. As a result, inferior products are manufactured, and thus productivity is decreased.